Which strength of fluoride in toothpaste is most effective?

Tooth decay (caries) is a widespread disease, affecting billions of people worldwide. Fluoride has long been used to prevent decay, through a variety of different methods including toothpaste, water, milk, mouthrinses, tooth gels and varnish. Regular toothbrushing is recommended to prevent decay and other oral diseases, and toothbrushing for 2 minutes twice daily with a fluoride toothpaste is generally recommended. The typical strength of regular or family toothpaste is around 1000 to 1500 parts per million (ppm) fluoride, but many other strengths are available worldwide. There is no minimum fluoride concentration, but the maximum permissible fluoride concentration for a toothpaste varies according to age and country. Higher concentrations are rarely available over the counter, and are classed as a prescription‐only medicine. Stronger fluoride toothpaste may offer greater protection against decay but also increases the risk of fluorosis (enamel defects) in developing teeth. This is an update of the Cochrane Review first published in 2010.

What was the research?

A systematic review to assess the effects of toothpastes of different fluoride strengths on preventing tooth decay in children, adolescents and adults.

Who conducted the research?

The research was conducted by a team led by Tanya Walsh, from the University of Manchester, UK, on behalf of Cochrane Oral Health. Helen V. Worthington, Anne-Marie Glenny, Valeria C.C. Marinho and Ana Jeroncic were also on the team.

What evidence was included in the review?

Authors from Cochrane Oral Health carried out this review and the evidence is current up to 15 August 2018. It includes 96 studies published between 1955 and 2014: seven studies with 11,356 randomised participants reported the effects of fluoride toothpaste up to 1500 ppm on the primary teeth; one study with 2500 randomised participants reported the effects of 1450 ppm toothpaste on the primary and permanent dentition; 85 studies with 48,804 randomised participants reported the effects of toothpaste up to 2400 ppm on the permanent teeth of children up to 18 years of age; and three studies with 2675 randomised participants reported the effects of up to 1100 ppm toothpaste on the permanent teeth of adults. Most studies assessed decay after participants had been using the toothpastes for 36 months.

What did the evidence say?

We present below findings for which there is moderate‐ or high‐certainty evidence.

In primary teeth of young children, brushing teeth with a toothpaste containing 1500 ppm fluoride reduced the amount of new decay when compared with non‐fluoride toothpaste; the amount of new decay was similar with 1055 ppm compared with 550 ppm fluoride toothpaste; and there was a slight reduction in the amount of new decay with 1450 ppm toothpaste compared with 440 ppm fluoride toothpaste.

Eighty‐one studies assessed the effects of different strengths of fluoride toothpaste compared against each other (seven different strengths in 21 combinations) in permanent teeth of children and adolescents. We found that there was less new decay when toothbrushing with toothpaste containing 1000 to 1250 ppm or 1450 to 1500 ppm fluoride compared with non‐fluoride toothpaste, and that toothbrushing with 1450 to 1500 ppm fluoride toothpaste reduced the amount of new decay more than 1000 to 1250 ppm toothpaste. We found that there was a similar amount of new decay when children and adolescents used a toothpaste of 1700 to 2200 ppm or 2400 to 2800 ppm fluoride compared to 1450 to 1500 ppm toothpaste. The evidence for the effects of other strengths of toothpaste was less certain.

In permanent teeth of adults of all ages, 1000 or 1100 ppm toothpaste reduced decay compared with non‐fluoride toothpaste.

Most studies did not measure harmful effects of toothpaste use, but when reported, effects such as soft tissue damage and tooth staining were minimal.

How good was the evidence?

There is high‐certainty evidence that toothpaste containing 1000 to 1250 ppm fluoride is more effective than non‐fluoride toothpaste. There is moderate‐certainty evidence for the other findings reported in ‘Main results’ above. For other toothpaste strengths compared against each other or against non‐fluoride toothpaste, there are too few studies with too few participants to have any clarity about the effects.

What are the implications for dentists and the general public?

Overall, there does appear to be some evidence of a dose‐response relationship in the caries‐preventive effects of fluoride in toothpastes, with the magnitude of the caries‐preventive effect estimate increasing as the distance between the lower and higher fluoride concentration increases.

The choice of fluoride toothpaste concentration should also be informed by concurrent fluoride use whether from self‐care measures (e.g. fluoride mouthrinse, community water fluoridation) or professionally applied sources (e.g. fluoride varnish), and consideration of the risk of fluorosis in the developing dentition of younger children.

What should researchers look at in the future?

Further research that directly compares the effects of fluoride toothpastes at lower fluoride concentrations with higher concentrations would greatly enhance the current evidence base, adding data and securing more precise estimates of effect. The evidence for the caries‐preventive effects of different fluoride toothpaste concentrations on the primary dentition of young children is particularly scarce. The potential caries‐preventive benefit from higher fluoride concentrations needs to be balanced against potential harms of fluorosis, and future research should explore the minimally effective fluoride concentration, balancing these benefits and harms. A consensus on the magnitude of a clinically important effect in this area would be useful not only for interpreting the evidence synthesis, but could be used to guide the design of future primary research.

It is reasonable to assume that differential treatment effects could be observed according to initial caries levels and uptake of additional sources of fluoride, through individualised oral care or community/school programmes. Adverse effects should be measured and reported, including long‐term assessment of fluorosis wherever possible. Taking these factors into account in the design and conduct of future research could provide a more realistic and meaningful estimate of the caries‐preventive effects of different fluoride toothpaste concentrations to inform consumers.

Link

Walsh  T, Worthington  HV, Glenny  AM, Marinho  VCC, Jeroncic  A. Fluoride toothpastes of different concentrations for preventing dental caries. Cochrane Database of Systematic Reviews 2019, Issue 3. Art. No.: CD007868. DOI: 10.1002/14651858.CD007868.pub3.

This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.